I am sure @dpsanders is much more knowledgeable than I am, but I find necessary to point that
The word
constis really a misnomer. It is not that the variable is constant. It is the variable type that is constant, which is quite different.
Is just completely wrong. The binding is constant, not the type. What difference this make? Exactly what @dpsanders pointed out, but trying to explain more exhaustively I would say: if the binding var1 is constant, then you cannot assign a new value/object for var1 (even of the same type), you can change a mutable field inside that value, but you cannot ever replace the entire object inside var1 by another.
This is: if tmp1 is an array, then you can add, remove, and replace elements; but you cannot never replace the original array by a brand new array (for example, to “empty” the array temporarily while keeping the old array in an auxiliary variable, with the intent of putting it back after, without having to make any copies, a swap basically); it is not the type that is fixed, it is that initial object (which can have mutable fields) that is fixed there forever. If it is an Int like in your example, this means you cannot never change that value (because an Int has no mutable fields inside it you can change). That name will point to the same ‘memory position’/reference/value its entire existence.